In recent years, with an object of shortening processes related to mounting methods of semiconductor chips, the use of pre-applied underfill film (PUF) wherein an underfill film is applied to electrodes of an integrated circuit (IC) has been investigated.
Packaging methods using this pre-applied underfill film are, for example, performed in the following manner (For example, refer to PTL 1).
Step A: An underfill film is applied to a wafer and the wafer is diced to obtain a semiconductor chip(s).
Step B: The semiconductor chip is aligned on the substrate after the application of the underfill film.
Step C: The semiconductor chip and substrate are thermally compressed together, electrical conduction is ensured using metallic bonding of solder bumps, and the semiconductor chip is bonded to the substrate by curing of the underfill film.
In such a packaging method, thermosetting adhesives using epoxy resin have been developed as adhesives to bond the solder bumps. In these adhesives, there have been proposed compositions using various curing agents including phenol, acid anhydride and amine type curing agent, among others, as a curing agent for epoxy resin (for example, see PTL 2).
As preventive measures for voids that might occur during thermocompression bonding, voidless packaging can be achieved by using a peroxide, among others, as a curing agent and by increasing curing speed; however, this degrades solder bonding properties.